Following successful immunization, the tumor microenvironment is dramatically altered. DC maturation occurs, and the DCs are induced to express strong costimulatory molecules able to effectively prime CD4 and CD8 T cell responses. When CD4 T cells are skewed to a Th1 phenotype, they further promote T cell priming and alter the local cytokine environment by releasing proinflammatory cytokines, such as IFN-γ and IL-12. This environment is favorable for tumor cell recognition and results in tumor rejection.